Method of separating strengthened glass

Title: Method of separating strengthened glass.Abstract: At least one damage line is formed within the strengthened glass sheet. The at least one damage line is formed outside the strengthened compressive stress surface layers and within the tensile stress layer of the strengthened glass sheet. The at least one damage line may be formed by laser treatment. A crack is initiated in the strengthened glass sheet and propagated along the at least one damage line to separate the strengthened glass sheet along the predetermined line, axis, or direction into at least two pieces.
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A method of cutting a glass sheet that has been thermally or chemically strengthened along a predetermined line, axis, or direction with high speed and with minimum damage on the cut edges. The strengthened glass sheet may be an aluminoborosilicate glass material having at least one alkali metal oxide modifier, and the ratio ...

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent application Ser. No. 12/388,837, filed Feb. 19, 2009, and entitled “Method of Separating Strengthened Glass.” This application is also related to U.S. Provisional Patent Application Ser. No. 61/235,767, filed Aug. 21, 2009, and entitled “Crack and Scratch Resistant Glass and Enclosures Made Therefrom,” but does not claim priority thereto.

BACKGROUND

Thermal tempering and chemical treatments by ion exchange are widely recognized means for strengthening glass. Glasses strengthened by such processes have compressive stress in the surface layers and tensile stress in the bulk.

Glasses that are either tempered or chemically strengthened are difficult, if not impossible, to cut or separate into pieces of desired shape and/or sizes. Conventional score-and-break techniques do not work because the initial crack does not propagate along the score line, but instead tends to bifurcate multiple times. Consequently, the glass sample usually breaks into multiple pieces. Cutting operations are therefore performed before carrying out strengthening operations.

SUMMARY

A method of cutting a glass sheet that has been thermally or chemically strengthened along a predetermined line, axis, or direction with high speed and with minimum damage on the cut edges is provided. The strengthened glass sheet may be cut into at least two pieces, one of which having a predetermined shape or dimension. At least one damage line is formed within the strengthened glass sheet. The at least one damage line is formed outside the strengthened compressive stress surface layers and within the tensile stress layer of the strengthened glass sheet. The at least one damage line may be formed by laser treatment. In one embodiment, a crack is initiated in the strengthened glass sheet (e.g., as an edge score) and propagated along the at least one damage line to separate the strengthened glass sheet along the predetermined line, axis, or direction into at least two pieces. In another embodiment, crack initiation and propagation is not utilized to separate the strengthened glass sheet but rather a UV-laser may be used without edge scoring.

In one embodiment, a method of separating a strengthened glass sheet, the method includes providing the strengthened glass sheet, the strengthened glass sheet having a first surface and a second surface. Each of the first surface and the second surface has a strengthened surface layer under a compressive stress and extending from the surface to a depth of layer, and a central region under tensile stress. The strengthened glass sheet is an aluminoborosilicate glass material having at least one alkali metal oxide modifier, and the ratio

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20101118|20100291353|separating strengthened glass|At least one damage line is formed within the strengthened glass sheet. The at least one damage line is formed outside the strengthened compressive stress surface layers and within the tensile stress layer of the strengthened glass sheet. The at least one damage line may be formed by laser treatment. |